Scanning ion conductance microscope with a capacitance-compensated current source amplifier

Kenta Nakazawa; Teruki Tsukamoto; Futoshi Iwata

doi:10.1063/5.0150948

Scanning ion conductance microscope with a capacitance-compensated current source amplifier

Rev Sci Instrum. 2023 Jul 1;94(7):073705. doi: 10.1063/5.0150948.

Authors

Kenta Nakazawa¹, Teruki Tsukamoto¹, Futoshi Iwata^{1

2

3}

Affiliations

¹ Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561, Japan.
² Graduate School of Medical Photonics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011, Japan.
³ Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011, Japan.

PMID: 37466407
DOI: 10.1063/5.0150948

Abstract

A high-speed imaging method for a scanning ion conductance microscope (SICM) based on a current source amplifier that compensates for unavoidable capacitance is proposed. The capacitance is generated on a side wall of a nanopipette in the principle of the SICM. The electrical response time is deteriorated due to the capacitance, and the probe overshoots the setpoint of the detection of the sample surface. A capacitance compensation circuit was installed in a feedback circuit of the current source amplifier. The proposed capacitance compensation method is useful because it can shorten the imaging time by only installing the compensation circuit in the ion current detection circuit of an existing SICM. The maximum approaching speeds with and without capacitance compensation were found to be 1050 and 450 µm/s, respectively. The approaching speed with capacitance compensation was 2.3 times faster than that without capacitance compensation. A topographic image of the test sample was successfully obtained at an approaching speed of 1050 µm/s. The images of microvillus dynamics of COS-7 cells were obtained at ∼23.4 s/frame as an application of the developed technology.